/*
 * Copyright (C) 2011 The Android Open Source Project
 * Copyright (C) 2011 Peter Kuterna
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.peterkuterna.android.apps.devoxxfrsched.ui;

import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.FrameLayout;
import android.widget.GridView;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.actionbarsherlock.app.SherlockFragment;

/**
 * Copy a the static library support version of the framework's
 * {@link android.app.ListFragment}, but then targetted for a {@link GridView}.
 */
public class GridFragment extends SherlockFragment {
	static final int INTERNAL_EMPTY_ID = 0x00ff0001;
	static final int INTERNAL_PROGRESS_CONTAINER_ID = 0x00ff0002;
	static final int INTERNAL_GRID_CONTAINER_ID = 0x00ff0003;

	final private Handler mHandler = new Handler();

	final private Runnable mRequestFocus = new Runnable() {
		public void run() {
			mGrid.focusableViewAvailable(mGrid);
		}
	};

	final private AdapterView.OnItemClickListener mOnClickListener = new AdapterView.OnItemClickListener() {
		public void onItemClick(AdapterView<?> parent, View v, int position,
				long id) {
			onGridItemClick((GridView) parent, v, position, id);
		}
	};

	ListAdapter mAdapter;
	GridView mGrid;
	View mEmptyView;
	TextView mStandardEmptyView;
	View mProgressContainer;
	View mGridContainer;
	CharSequence mEmptyText;
	boolean mGridShown;

	public GridFragment() {
	}

	/**
	 * Provide default implementation to return a simple grid view. Subclasses
	 * can override to replace with their own layout. If doing so, the returned
	 * view hierarchy <em>must</em> have a GridView whose id is
	 * {@link android.R.id#list android.R.id.list} and can optionally have a
	 * sibling view id {@link android.R.id#empty android.R.id.empty} that is to
	 * be shown when the list is empty.
	 * 
	 * <p>
	 * If you are overriding this method with your own custom content, consider
	 * including the standard layout {@link android.R.layout#list_content} in
	 * your layout file, so that you continue to retain all of the standard
	 * behavior of GridFragment. In particular, this is currently the only way
	 * to have the built-in indeterminant progress state be shown.
	 */
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		final Context context = getActivity();

		FrameLayout root = new FrameLayout(context);

		// ------------------------------------------------------------------

		LinearLayout pframe = new LinearLayout(context);
		pframe.setId(INTERNAL_PROGRESS_CONTAINER_ID);
		pframe.setOrientation(LinearLayout.VERTICAL);
		pframe.setVisibility(View.GONE);
		pframe.setGravity(Gravity.CENTER);

		ProgressBar progress = new ProgressBar(context, null,
				android.R.attr.progressBarStyleLarge);
		pframe.addView(progress, new FrameLayout.LayoutParams(
				ViewGroup.LayoutParams.WRAP_CONTENT,
				ViewGroup.LayoutParams.WRAP_CONTENT));

		root.addView(pframe, new FrameLayout.LayoutParams(
				ViewGroup.LayoutParams.FILL_PARENT,
				ViewGroup.LayoutParams.FILL_PARENT));

		// ------------------------------------------------------------------

		FrameLayout gframe = new FrameLayout(context);
		gframe.setId(INTERNAL_GRID_CONTAINER_ID);

		TextView tv = new TextView(context);
		tv.setId(INTERNAL_EMPTY_ID);
		tv.setGravity(Gravity.CENTER);
		gframe.addView(tv, new FrameLayout.LayoutParams(
				ViewGroup.LayoutParams.FILL_PARENT,
				ViewGroup.LayoutParams.FILL_PARENT));

		GridView gv = new GridView(context);
		gv.setId(android.R.id.list);
		gv.setDrawSelectorOnTop(false);
		gframe.addView(gv, new FrameLayout.LayoutParams(
				ViewGroup.LayoutParams.FILL_PARENT,
				ViewGroup.LayoutParams.FILL_PARENT));

		root.addView(gframe, new FrameLayout.LayoutParams(
				ViewGroup.LayoutParams.FILL_PARENT,
				ViewGroup.LayoutParams.FILL_PARENT));

		// ------------------------------------------------------------------

		root.setLayoutParams(new FrameLayout.LayoutParams(
				ViewGroup.LayoutParams.FILL_PARENT,
				ViewGroup.LayoutParams.FILL_PARENT));

		return root;
	}

	/**
	 * Attach to grid view once the view hierarchy has been created.
	 */
	@Override
	public void onViewCreated(View view, Bundle savedInstanceState) {
		super.onViewCreated(view, savedInstanceState);
		ensureGrid();
	}

	/**
	 * Detach from grid view.
	 */
	@Override
	public void onDestroyView() {
		mHandler.removeCallbacks(mRequestFocus);
		mGrid = null;
		mGridShown = false;
		mEmptyView = mProgressContainer = mGridContainer = null;
		mStandardEmptyView = null;
		super.onDestroyView();
	}

	/**
	 * This method will be called when an item in the grid is selected.
	 * Subclasses should override. Subclasses can call
	 * getGridView().getItemAtPosition(position) if they need to access the data
	 * associated with the selected item.
	 * 
	 * @param gv
	 *            The GridView where the click happened
	 * @param v
	 *            The view that was clicked within the GridView
	 * @param position
	 *            The position of the view in the grid
	 * @param id
	 *            The row id of the item that was clicked
	 */
	public void onGridItemClick(GridView gv, View v, int position, long id) {
	}

	/**
	 * Provide the cursor for the grid view.
	 */
	public void setListAdapter(ListAdapter adapter) {
		boolean hadAdapter = mAdapter != null;
		mAdapter = adapter;
		if (mGrid != null) {
			mGrid.setAdapter(adapter);
			if (!mGridShown && !hadAdapter) {
				// The grid was hidden, and previously didn't have an
				// adapter. It is now time to show it.
				setGridShown(true, getView().getWindowToken() != null);
			}
		}
	}

	/**
	 * Set the currently selected grid item to the specified position with the
	 * adapter's data
	 * 
	 * @param position
	 */
	public void setSelection(int position) {
		ensureGrid();
		mGrid.setSelection(position);
	}

	/**
	 * Get the position of the currently selected grid item.
	 */
	public int getSelectedItemPosition() {
		ensureGrid();
		return mGrid.getSelectedItemPosition();
	}

	/**
	 * Get the cursor row ID of the currently selected grid item.
	 */
	public long getSelectedItemId() {
		ensureGrid();
		return mGrid.getSelectedItemId();
	}

	/**
	 * Get the activity's grid view widget.
	 */
	public GridView getGridView() {
		ensureGrid();
		return mGrid;
	}

	/**
	 * The default content for a GridFragment has a TextView that can be shown
	 * when the grid is empty. If you would like to have it shown, call this
	 * method to supply the text it should use.
	 */
	public void setEmptyText(CharSequence text) {
		ensureGrid();
		if (mStandardEmptyView == null) {
			throw new IllegalStateException(
					"Can't be used with a custom content view");
		}
		mStandardEmptyView.setText(text);
		if (mEmptyText == null) {
			mGrid.setEmptyView(mStandardEmptyView);
		}
		mEmptyText = text;
	}

	/**
	 * Control whether the grid is being displayed. You can make it not
	 * displayed if you are waiting for the initial data to show in it. During
	 * this time an indeterminant progress indicator will be shown instead.
	 * 
	 * <p>
	 * Applications do not normally need to use this themselves. The default
	 * behavior of GridFragment is to start with the grid not being shown, only
	 * showing it once an adapter is given with
	 * {@link #setListAdapter(ListAdapter)}. If the grid at that point had not
	 * been shown, when it does get shown it will be do without the user ever
	 * seeing the hidden state.
	 * 
	 * @param shown
	 *            If true, the grid view is shown; if false, the progress
	 *            indicator. The initial value is true.
	 */
	public void setGridShown(boolean shown) {
		setGridShown(shown, true);
	}

	/**
	 * Like {@link #setGridShown(boolean)}, but no animation is used when
	 * transitioning from the previous state.
	 */
	public void setGridShownNoAnimation(boolean shown) {
		setGridShown(shown, false);
	}

	/**
	 * Control whether the grid is being displayed. You can make it not
	 * displayed if you are waiting for the initial data to show in it. During
	 * this time an indeterminant progress indicator will be shown instead.
	 * 
	 * @param shown
	 *            If true, the grid view is shown; if false, the progress
	 *            indicator. The initial value is true.
	 * @param animate
	 *            If true, an animation will be used to transition to the new
	 *            state.
	 */
	private void setGridShown(boolean shown, boolean animate) {
		ensureGrid();
		if (mProgressContainer == null) {
			throw new IllegalStateException(
					"Can't be used with a custom content view");
		}
		if (mGridShown == shown) {
			return;
		}
		mGridShown = shown;
		if (shown) {
			if (animate) {
				mProgressContainer.startAnimation(AnimationUtils.loadAnimation(
						getActivity(), android.R.anim.fade_out));
				mGridContainer.startAnimation(AnimationUtils.loadAnimation(
						getActivity(), android.R.anim.fade_in));
			} else {
				mProgressContainer.clearAnimation();
				mGridContainer.clearAnimation();
			}
			mProgressContainer.setVisibility(View.GONE);
			mGridContainer.setVisibility(View.VISIBLE);
		} else {
			if (animate) {
				mProgressContainer.startAnimation(AnimationUtils.loadAnimation(
						getActivity(), android.R.anim.fade_in));
				mGridContainer.startAnimation(AnimationUtils.loadAnimation(
						getActivity(), android.R.anim.fade_out));
			} else {
				mProgressContainer.clearAnimation();
				mGridContainer.clearAnimation();
			}
			mProgressContainer.setVisibility(View.VISIBLE);
			mGridContainer.setVisibility(View.GONE);
		}
	}

	/**
	 * Get the ListAdapter associated with this activity's GridView.
	 */
	public ListAdapter getListAdapter() {
		return mAdapter;
	}

	private void ensureGrid() {
		if (mGrid != null) {
			return;
		}
		View root = getView();
		if (root == null) {
			throw new IllegalStateException("Content view not yet created");
		}
		if (root instanceof GridView) {
			mGrid = (GridView) root;
		} else {
			mStandardEmptyView = (TextView) root
					.findViewById(INTERNAL_EMPTY_ID);
			if (mStandardEmptyView == null) {
				mEmptyView = root.findViewById(android.R.id.empty);
			} else {
				mStandardEmptyView.setVisibility(View.GONE);
			}
			mProgressContainer = root
					.findViewById(INTERNAL_PROGRESS_CONTAINER_ID);
			mGridContainer = root.findViewById(INTERNAL_GRID_CONTAINER_ID);
			View rawGridView = root.findViewById(android.R.id.list);
			if (!(rawGridView instanceof GridView)) {
				if (rawGridView == null) {
					throw new RuntimeException(
							"Your content must have a GridView whose id attribute is "
									+ "'android.R.id.list'");
				}
				throw new RuntimeException(
						"Content has view with id attribute 'android.R.id.list' "
								+ "that is not a GridView class");
			}
			mGrid = (GridView) rawGridView;
			if (mEmptyView != null) {
				mGrid.setEmptyView(mEmptyView);
			} else if (mEmptyText != null) {
				mStandardEmptyView.setText(mEmptyText);
				mGrid.setEmptyView(mStandardEmptyView);
			}
		}
		mGridShown = true;
		mGrid.setOnItemClickListener(mOnClickListener);
		if (mAdapter != null) {
			ListAdapter adapter = mAdapter;
			mAdapter = null;
			setListAdapter(adapter);
		} else {
			// We are starting without an adapter, so assume we won't
			// have our data right away and start with the progress indicator.
			if (mProgressContainer != null) {
				setGridShown(false, false);
			}
		}
		mHandler.post(mRequestFocus);
	}
}
